Structural behavior of reinforced concrete tunnel linings with synthetic fibers addition

Abstract

Fiber-reinforced-concrete has been widely used in underground structures in recent years, especially in tunnel linings. Compared with steel fiber reinforced concrete, synthetic fiber reinforced concrete not only has a considerable structural bearing capacity but also shows a better corrosion resistance and durability. However, most researchers focused on the cracking resistance property of synthetic fiber reinforced concrete instead of its mechanical contribution. Besides, experiments were carried out mostly on structural components such as beams or segments. There is little information about the performance of synthetic fiber reinforced concrete in full-scale tunnel lining rings. In this study, full-scale experiments were carried out for tunnel lining specimens with synthetic fiber reinforced concrete and traditional reinforced concrete. The experimental results are compared to evaluate the different structural behaviors between the fiber-reinforced and the steel-reinforced concrete specimens. The failure mechanism of the synthetic fiber reinforced concrete tunnel lining was investigated and compared to that of the traditional RC tunnel lining. The results show that the addition of synthetic fibers can delay the occurrence of yielding state and lead to a higher yielding load compared to the traditional RC specimen. The approach of reducing steel reinforcement by adding synthetic fibers appears to be a viable method to optimize the lining design. The differences in cracks, bearing capacity, stiffness, and other mechanical behaviors between the synthetic fiber reinforced concrete and the traditional reinforced concrete tunnel lining structures are also discussed. The results show that the synthetic fiber reinforced concrete tunnel lining structure has a different failure mechanism and better performance than the traditional RC tunnel lining structures. With a 47% reduction of steel reinforcement in the lining segments, the bearing capacity and other mechanical properties of the synthetic fiber reinforced concrete tunnel lining structure can still be comparable to those of the traditional RC tunnel lining structures.